High reliability joint for manufacture of pipe

ABSTRACT

This invention relates to a novel joint particularly well suited for use in the continuous and rapid manufacture of high pressure pipe, tubing or the like. The pipe so manufactured may be made in a wide range of diameters and helix angles, with my novel joint possessing sufficient mechanical strength that unraveling of the pipe joint simply will not occur. For pipes to be manufactured for use underwater or underground, or to carry particularly high pressure, I may additionally utilize brazing material on a continuous basis along the joint, thus assuring against porosity, even under high stress conditions.

Iinited States Patent aika [54] HIGH RELIABILITY JOINT FOR MANUFACTUREOF PIPE [56] References Cited UNITED STATES PATENTS 1,933,279 10/1933Quarnstrom ..138/156 1,502,052 7/1924 Naylor ....138/l54 X 1,943,035l/1934 Naylor ....l38/154 X 1,952,955 3/1934 Trageser ..138/17l2,067,801 l/l937 Taylor ..138/171 X 2,288,094 6/1942 Karmazim ..138/l54X 2,884,958 5/1959 Asselin ..138/l7l 3,199,541 8/1965 Richitelli..138/154 X FOREIGN PATENTS OR APPLICATIONS 1,487,218 5/1967 France..138/154 Primary Examiner-Herbert F. Ross Attorney-Julian C. Renfro[57] ABSTRACT This invention relates to a novel joint particularly wellsuited for use in the continuous and rapid manufacture of high pressurepipe, tubing or the like. The pipe so manufactured may be made in a widerange of diameters and helix angles, with my novel joint possessingsufficient'mechanical strength that unraveling of the pipe joint simplywill not occur. For pipes to be manufactured for use underwater orunderground, or to carry particularly high pressure, I may additionallyutilize brazing material on a continuous basis along the joint, thusassuring against porosity, even under high stress conditions.

6 Claims, 3 Drawing Figures PATENTEDAPR 18 i972 INVENTOR.

ROBERT STICKNEY KAFKA HIGH RELIABILITY JOINT FOR MANUFACTURE OF PIPEThis invention relates to a novel joint configuration usable for examplein the creation of pipes, tubing or the like, and more particularly to ajoint configuration possessing mechanical strength before as well asafter welding, which joint can be readily adapted to highly satisfactorypressure proofing procedures.

In the past a number of joints suitable for use in the manufacture ofpipe and conduit have been proposed. Some of these joints have beenself-clinching to such an extent that flexible helical conduit in thenature of BX cable could be rapidly produced at minimum expense.However, such pipe or conduit could not withstand internal or externalpressure and such techniques could obviously not be employed in theconstruction of pipes designed for a hostile environment, such as foruse in underground or underwater locations.

Other procedures have been proposed involving the use of metal stripshaving pre-prepared left and right edges so that when wound into agenerally helical arrangement, adjacent edges could be welded orotherwise secured together to create a pipe or conduit that wouldwithstand internal pressure. How-. ever, the edges of such prior artarrangements did not physically and mechanically interfit, and thefinished pipe could not withstand any sizable amount of mechanicalloading. Moreover, such pipe was suitable only for low pressureapplications.

In accordance with this invention I have provided a novel joint suitablefor use in making conduit, pipe, tubing or the like, which possessesgreat strength, and which joints can be fabricated easily andeconomically so that finished pipe suitable for use in underground orunderwater locations can be made in the size desired at a locationadjacent to the site of intended use.

I typically work with malleable strip material such as of steel,aluminum or plastic of comparatively thick gauge, and by the use of moreor less conventional rolling or forming techniques prepare the oppositeedges of the strip material to form novel male and femaleconfigurations, so that at the time joining of the two edges is to bebrought about, the edges will physically and mechanically interfit.

As set forth in the Mar. 11, 1968 edition of Product Engineering on page109, various new techniques are now available for making large-diametertubing in accordance with spiral winding techniques, with mechanicallocking of adjacent edges being utilized instead of welding procedures.My present invention is to some extent based upon such principles, inthat during the manufacture of tubing utilizing a spiral lock scam, Iutilize strip material having opposite edges that interfit with asubstantial amount of self alignment, resulting in initial jointstrength. Certain techniques may be utilized for clinching the joint,with thereafter appropriate heating means being employed so that theinterfitting male and female edges will be heated to an extent necessaryfor diffusion welding. Immediately thereafter the heated edges arepassed through working means designed to tightly compress and lock thejoints into a highly satisfactory seam in accordance with diffusionwelding techniques. Then, the pipe is moved into a position forimmediate use.

Significantly, my novel joint technique possesses mechanical strengthboth before and after welding, and further, when metallic pipe isinvolved, readily lends itself to .a highly advantageous pressure leaksealing technique such that the finished pipe or conduit can be exposedto pressures in the vicinity of several thousands pounds per squareinch. This latter technique may involve the use of brazing material orthe like inserted directly into the interfitted joints subsequent toheating but prior to diffusion welding of the joints. The basic physicalproperty of the inserted material is its high fluidity under thiscircumstance, with the result being that all possible interstices of thejoint are effectively closed, and porosity prevented.

It is therefore an object of my invention to provide a joint techniquethat lends itself to a wide range of pipe and joint fabricationrequirements. 7

It is another object of my invention to provide a pipe joint techniqueinvolving .novel interfitting edge beads that maintain individualitythrough to the finished joint, thus possessing strength not possessed byprior art techniques wherein the adjacent beads disappeared during thewelding process.

It is still another object of my invention to provide a novel jointtechnique by the use of which pipe having an entirely smooth innersurface may be created.

It should be noted'that my technique makes it possible for male andfemale edge beads in accordance with my novel concepts to be utilized inthe manufacture of conduit at a wide range of helix angles. My conceptsmay be employed at virtually any helix angle between 0 and with thediameter of the pipe or conduit increasing as a function of the tangentof the helix angle.

These and other objects, features and advantages of my invention will bemore apparent from a study of the appended drawings in which:

FIG. 1 illustrates a cross-section of a typical finished pipe joint inaccordance with my invention;

FIG. 2 illustrates the pipe joint at an earlier period in time, shortlyafter the male and female members have been initially interfitted; and

FIG. 3 is a perspective view to a smaller scale of a portion of afinished pipe in accordance with my technique.

Referring to FIGS. 1 and 2 it will be noted that strip material 1 andstrip material 2 have each been provided with a distinctive edgeconfiguration such that the edges may be initially interfitted in thegeneral manner shown in FIG. 2 and even then possess some mechanicalstrength. This fact is of consequence when it is realized that someapplications of my novel joint technique may involve the manufacture ofpipe having a helical joint, with strip material 1 and strip material 2depicted in FIGS. 1 and 2 actually being different portions of the sameoriginal piece of strip material that has been helically wound in thegeneral manner shown in FIG. 3.

It should be noted in FIGS. 1 and 2 that the right hand edge of piece 1has been rolled so as to form an inclined flange 8 as a continuation ofthe upper and lower surfaces of piece or member 1 extending upwardly andforwardly so that the upper surface of the flange extends above thelevel of the top surface of piece 1 and has an enlarged transverselypositioned oval shaped bulbous part 4 at the extremity of said flange,said bulbous part including an edge portion forming an upper hookportion 5 extending transversely of the flange, upwardly and rearwardly,and an opposite edge portion forming a lower hook portion 5a extendingtransversely of the flange downwardly and forwardly. The flange 8, thebulbous part 4, the upper hook portion 5 and the lower hook portion 5aall extend continuously along the edge of piece 1. On the other hand,the left hand edge of piece 2 has been rolled or otherwise configured soas to have a hook portion 10 that can somewhat encircle and interfitwith hook portion 5, as well as a heel portion 13 that can be broughtinto tightly interfitting contact with the hook portion 5a as a resultof the application of vertical forces. Although my joint may be producedwithout heat being involved, the heating of the edge members materiallyreduces the working forces and thus enables the size of the equipment tobe reduced.

Significantly, the upper portion of the left edge of piece 2 isconfigured so that when the interfltting edges have been put together, abalanced arrangement is created such that there is no tendency for thejoint to shift either to the right or to the left during the subsequentrolling and/or forging process. A rolling or forging technique istypically utilized for converting the joint shown in FIG. 2 into thefinished joint shown in FIG. 1, and because a balanced force system isutilized, this allows a highly desirable large movement of metal (orplastic) to take place with no external restraints being involved. Inother words, a groove on the upper roller or forging hammer interfitswith the external portion 3 of hook 10, thereby preventing a tendencytoward lateral shift. Thus, the channel member has a rounded exteriorportion configured such that a balanced force is involved when heat andpressure are utilized to accomplish diffusion welding.

The channel or groove continuously formed along the edge of piece 2 isopen in the direction such that the hook portion of piece 1 tends tomove as a result of elasticity or springiness of the material, towardrather than away from the inner portion of the book 10. The dimensionthat the channel is open to receive the hook is represented by thedimension 9 in FIG. 2.

After the edges have been interfitted in the manner shown in FIG. 2,heating techniques such as may employ a gas flame, an induction heateror the like are utilized so as to bring these edges up to a desiredtemperature. When steel is involved, the temperature is quite high,whereas for aluminum and plastic, the temperatures are proportionatelylower. Immediately after heating, forming means such as rolls ofappropriate contour are utilized for applying vertical forces to bringabout closure of the portions 10 and 13 about the hook portions and 5ain the general manner shown in FIG. 1, thus to accomplish theconstruction of a highly satisfactory joint possessing mechanicalstrength both from the interior as well as exterior directions. Itshould be noted that considerable working of the malleable materialshown in FIG. 2 is involved in causing the toe 14 to scrape along thetop of piece 1, and heel 13 to move so that surface 12 closely conformsto the lower contour of piece 1 adjacent the lower hook portion 5a asindicated at 16. These motions and the accompanying material working aredesirable from several metallurgical considerations, such as thecleaning of the upper surface of piece 1 by this scraping action, andthe increase of strength of all components. The amount of flow ofthematerial necessary to effect the joint can be controlled in light of thenature ofthe material. It should be noted also that part of the channelin closed position fits closely against the upper surface of member 1and the upper surface of flange 8 as well as the hook portion 5, whilepart 13 of the channel in closed position fits closely against the lowersurface of flange 8 as well as the hook portion 5a and the lower surfaceof part 13 is flush with the lower surfaces of members 1 and 2.

When working with steel, my technique can be extended so as to involvethe addition of brazing material 11 into the groove 6 adjacent theuppermost portion of hook 5, such being accomplished immediately priorto the closure of the joint ofthe piece 2. Because ofthe considerableheat involved, the brazing material is caused to fluidize and permeate apart of the joint, the extent depending upon the amount of brazingmaterial used, to effectively seal it as shown at 7 against leakage eventhough the joint may thereafter be subject to internal or externalpressures in the vicinity of several thousand pounds per square inch.This point is important inasmuch as the appearance of brazing materialoutside the joint is usually undesirable in that such material mightwell be attacked as a result ofelectrolytic action.

With regard to the finished joint shown in FIG. 1, four forces areillustrated. These are F, indicating pull force, F, indicatingcompression force, F meaning force upward (or internal) force, and Fmeaning downward (external or collapsing) force. A fifth force notillustrated here is slip force, or force along the joint.

Examination of this novel joint configuration reveals that all theseforces are resisted by the mechanical shape of the joint, and that thewelding and brazing merely enhances its strength. The high mechanicalstrength inherent in my joint means that the finished joint has higherstrength than the parent material. This is of consequence when it isrealized that in a helical joint, the hoop strength of the parentmaterial cannot be relied upon to support the joint. The initialclinching brought about in FIG. 2 is usually sufficient to prevent slipalong the joint, even before any working of the material is broughtabout.

It should be noted that the discrete bead in accordance with myinvention acts as a reinforcement to prevent the occurrence of kinkingor collapse of the pipe when the pipe has that may be used with a widerange of types of malleable material. Although I may utilize this jointin joining flat sections of material together, this joint is admirablysuited for use when pipe is being manufactured involving a helicaljoint. This latter is true from the several standpoints that the edgeconfigurations can be created immediately before the male and femaleedges are to be brought together; the edges fit together easily andstrongly resist separation; and closure of the joint can be effected ona continuous basis. Balanced forces are involved in creating a joint,the joint strengthens the pipe being formed, and the joint does notinhibit flow through the pipe. Inasmuch as my joint possessesconsiderable mechanical strength from many standpoints, unraveling ofpipe simply will not occur. Because of these attributes, the pipe may belowered directly into the water or earth on a continuous basis as thepipe is being made.

Other configurations and utilizations of my invention will be apparentto those skilled in the art, and I am not to be restricted to thoseshown and described herein except as required by the scope of theappended claims.

lclaim:

1. An interlocking joint suitable for use in a tube made utilizing theforging characteristics of malleable material comprising a member with afirst edge having a continuous upwardly and forwardly extending flangeat the end of which is formed a continuous transversely extendingbulbous portion, said bulbous portion protruding above the top surfaceof said member and including a continuous upper hook portion extendingupwardly and rearwardly and a continuous lower hook portion extendingdownwardly and forwardly, and a second edge along which a continuouschannel is formed, said channel being open to an extent sufficient toreceive said bulbous portion including said upper hook portion and saidlower hook portion, said channel being then closed so as to fit aroundsaid bulbous portion including said upper hook portion and said lowerhook portion in a tight and permanent manner and the joint being welded.

2. The joint as defined in claim 1 in which brazing material is disposedinside said channel along said bulbous portion at the time of closure ofthe joint, to assure against porosity in said joint.

3. The joint as defined in claim 1 in which said channel member has arounded exterior portion configured such that a balanced force isinvolved when heat and pressure are utilized to accomplish diffusionwelding.

4. A tube having a spiral seam comprising an interlocked joint asclaimed in claim 1.

5. A tube as claimed in claim 4 in which said joint is disposed entirelyon the exterior leaving the interior of the tube without internalobstruction due to the joint.

6. An interlocked joint as claimed in claim 1, in which said flangeforms a continuation of the upper and lower surfaces of said member anda major portion of said bulbous portion extends above the upper surfaceof said member, the part of the channel which when closed fits aroundsaid upper hook portion also fitting closely against the flange and theupper surface of said member, and the part of the channel which whenclosed fits around the lower hook portion also fitting closely againstthe flange and having a lower surface in the same plane as the lowersurface of the member.

1. An interlocking joint suitable for use in a tube made utilizing theforging characteristics of malleable material comprising a member with afirst edge having a continuous upwardly and forwardly extending flangeat the end of which is formed a continuous transversely extendingbulbous portion, said bulbous portion protruding above the top surfaceof said member and including a continuous upper hook portion extendingupwardly and rearwardly and a continuous lower hook portion extendingdownwardly and forwardly, And a second edge along which a continuouschannel is formed, said channel being open to an extent sufficient toreceive said bulbous portion including said upper hook portion and saidlower hook portion, said channel being then closed so as to fit aroundsaid bulbous portion including said upper hook portion and said lowerhook portion in a tight and permanent manner and the joint being welded.2. The joint as defined in claim 1 in which brazing material is disposedinside said channel along said bulbous portion at the time of closure ofthe joint, to assure against porosity in said joint.
 3. The joint asdefined in claim 1 in which said channel member has a rounded exteriorportion configured such that a balanced force is involved when heat andpressure are utilized to accomplish diffusion welding.
 4. A tube havinga spiral seam comprising an interlocked joint as claimed in claim
 1. 5.A tube as claimed in claim 4 in which said joint is disposed entirely onthe exterior leaving the interior of the tube without internalobstruction due to the joint.
 6. An interlocked joint as claimed inclaim 1, in which said flange forms a continuation of the upper andlower surfaces of said member and a major portion of said bulbousportion extends above the upper surface of said member, the part of thechannel which when closed fits around said upper hook portion alsofitting closely against the flange and the upper surface of said member,and the part of the channel which when closed fits around the lower hookportion also fitting closely against the flange and having a lowersurface in the same plane as the lower surface of the member.